Multi-field, multi-word, match without query_string

What you are looking for is the multi-match query, but it doesn't perform in quite the way you would like.

Compare the output of validate for multi_match vs query_string.

multi_match (with operator and) will make sure that ALL terms exist in at least one field:

curl -XGET 'http://127.0.0.1:9200/_validate/query?pretty=1&explain=true'  -d '
{
   "multi_match" : {
      "operator" : "and",
      "fields" : [
         "firstname",
         "lastname"
      ],
      "query" : "john smith"
   }
}
'

# {
#    "_shards" : {
#       "failed" : 0,
#       "successful" : 1,
#       "total" : 1
#    },
#    "explanations" : [
#       {
#          "index" : "test",
#          "explanation" : "((+lastname:john +lastname:smith) | (+firstname:john +firstname:smith))",
#          "valid" : true
#       }
#    ],
#    "valid" : true
# }

While query_string (with default_operator AND) will check that EACH term exists in at least one field:

curl -XGET 'http://127.0.0.1:9200/_validate/query?pretty=1&explain=true'  -d '
{
   "query_string" : {
      "fields" : [
         "firstname",
         "lastname"
      ],
      "query" : "john smith",
      "default_operator" : "AND"
   }
}
'

# {
#    "_shards" : {
#       "failed" : 0,
#       "successful" : 1,
#       "total" : 1
#    },
#    "explanations" : [
#       {
#          "index" : "test",
#          "explanation" : "+(firstname:john | lastname:john) +(firstname:smith | lastname:smith)",
#          "valid" : true
#       }
#    ],
#    "valid" : true
# }

So you have a few choices to achieve what you are after:

1. Preparse the search terms, to remove things like wildcards, etc, before using the query_string

2. Preparse the search terms to extract each word, then generate a multi_match query per word

3. Use index_name in your mapping for the name fields to index their data into a single field, which you can then use for search. (like your own custom all field):

As follows:

curl -XPUT 'http://127.0.0.1:9200/test/?pretty=1'  -d '
{
   "mappings" : {
      "test" : {
         "properties" : {
            "firstname" : {
               "index_name" : "name",
               "type" : "string"
            },
            "lastname" : {
               "index_name" : "name",
               "type" : "string"
            }
         }
      }
   }
}
'

curl -XPOST 'http://127.0.0.1:9200/test/test?pretty=1'  -d '
{
   "firstname" : "john",
   "lastname" : "smith"
}
'

curl -XGET 'http://127.0.0.1:9200/test/test/_search?pretty=1'  -d '
{
   "query" : {
      "match" : {
         "name" : {
            "operator" : "and",
            "query" : "john smith"
         }
      }
   }
}
'

# {
#    "hits" : {
#       "hits" : [
#          {
#             "_source" : {
#                "firstname" : "john",
#                "lastname" : "smith"
#             },
#             "_score" : 0.2712221,
#             "_index" : "test",
#             "_id" : "VJFU_RWbRNaeHF9wNM8fRA",
#             "_type" : "test"
#          }
#       ],
#       "max_score" : 0.2712221,
#       "total" : 1
#    },
#    "timed_out" : false,
#    "_shards" : {
#       "failed" : 0,
#       "successful" : 5,
#       "total" : 5
#    },
#    "took" : 33
# }

Note however, that firstname and lastname are no longer searchable independently. The data for both fields has been indexed into name.

You could use multi-fields with the path parameter to make them searchable both independently and together, as follows:

curl -XPUT 'http://127.0.0.1:9200/test/?pretty=1'  -d '
{
   "mappings" : {
      "test" : {
         "properties" : {
            "firstname" : {
               "fields" : {
                  "firstname" : {
                     "type" : "string"
                  },
                  "any_name" : {
                     "type" : "string"
                  }
               },
               "path" : "just_name",
               "type" : "multi_field"
            },
            "lastname" : {
               "fields" : {
                  "any_name" : {
                     "type" : "string"
                  },
                  "lastname" : {
                     "type" : "string"
                  }
               },
               "path" : "just_name",
               "type" : "multi_field"
            }
         }
      }
   }
}
'

curl -XPOST 'http://127.0.0.1:9200/test/test?pretty=1'  -d '
{
   "firstname" : "john",
   "lastname" : "smith"
}
'

Searching the any_name field works:

curl -XGET 'http://127.0.0.1:9200/test/test/_search?pretty=1'  -d '
{
   "query" : {
      "match" : {
         "any_name" : {
            "operator" : "and",
            "query" : "john smith"
         }
      }
   }
}
'

# {
#    "hits" : {
#       "hits" : [
#          {
#             "_source" : {
#                "firstname" : "john",
#                "lastname" : "smith"
#             },
#             "_score" : 0.2712221,
#             "_index" : "test",
#             "_id" : "Xf9qqKt0TpCuyLWioNh-iQ",
#             "_type" : "test"
#          }
#       ],
#       "max_score" : 0.2712221,
#       "total" : 1
#    },
#    "timed_out" : false,
#    "_shards" : {
#       "failed" : 0,
#       "successful" : 5,
#       "total" : 5
#    },
#    "took" : 11
# }

Searching firstname for john AND smith doesn't work:

curl -XGET 'http://127.0.0.1:9200/test/test/_search?pretty=1'  -d '
{
   "query" : {
      "match" : {
         "firstname" : {
            "operator" : "and",
            "query" : "john smith"
         }
      }
   }
}
'

# {
#    "hits" : {
#       "hits" : [],
#       "max_score" : null,
#       "total" : 0
#    },
#    "timed_out" : false,
#    "_shards" : {
#       "failed" : 0,
#       "successful" : 5,
#       "total" : 5
#    },
#    "took" : 2
# }

But searching firstname for just john works correctly:

curl -XGET 'http://127.0.0.1:9200/test/test/_search?pretty=1'  -d '
{
   "query" : {
      "match" : {
         "firstname" : {
            "operator" : "and",
            "query" : "john"
         }
      }
   }
}
'

# {
#    "hits" : {
#       "hits" : [
#          {
#             "_source" : {
#                "firstname" : "john",
#                "lastname" : "smith"
#             },
#             "_score" : 0.30685282,
#             "_index" : "test",
#             "_id" : "Xf9qqKt0TpCuyLWioNh-iQ",
#             "_type" : "test"
#          }
#       ],
#       "max_score" : 0.30685282,
#       "total" : 1
#    },
#    "timed_out" : false,
#    "_shards" : {
#       "failed" : 0,
#       "successful" : 5,
#       "total" : 5
#    },
#    "took" : 3
# }

I would rather avoid using query_string in case the user passes "OR", "AND" and any of the other advanced params.

In my experience, escaping the special characters with backslash is a simple and effective solution. The list can be found in the documentation http://lucene.apache.org/core/4_5_0/queryparser/org/apache/lucene/queryparser/classic/package-summary.html#package_description, plus AND/OR/NOT/TO.