Searching in values of a redis db

Redis is for use cases where you need to access and update data at very high frequency and where you benefit from use of data structures (hashes, sets, lists, strings, or sorted sets). It's made to fill very specific use cases. If you have a general use case like very flexible searching, you'd be much better served by something built for this purpose like elastic search or SOLR.

That said, if you must do this in Redis, here's how I'd do it (assuming users can share names and phone numbers):

name:some_name -> set([id1, id2, etc...])
name:some_other_name -> set([id3, id4, etc...])

phone:some_phone -> set([id1, id3, etc...])
phone:some_other_phone -> set([id2, id4, etc...])

id1 -> {'name' : 'bob', 'phone' : '123-456-7891', etc...}
id2 -> {'name' : 'alice', 'phone' : '987-456-7891', etc...}

In this case, we're making a new key for every name (prefixed with "name:") and every phone number (prefixed "phone:"). Each key points to a set of ids that have all the info you want for a user. When you search, for a phone, for example, you'll do:

HGETALL 'phone:123-456-7891'

and then loop through the results and return whatever info on each (name in our example) in your language of choice (you can do this whole thing in server-side Lua on the Redis box to go even faster and avoid network back-and-forth, if you want):

for id in results:
    HGET id 'name'

You're cost here will be O(m) where m is the number of users with the given phone number, and this will be a very fast operation on Redis because of how optimized it is for speed. It'll be overkill in your case because you probably don't need things to go so fast, and you'd prefer having flexible search, but this is how you would do it.

redis is awesome, but it's not built for searching on anything other than keys. You simply cant query on values without building extra data sets to store items to facilitate such querying, but even then you don't get true search, just more maintenance, inefficient use of memory, yada, yada...

This question has already been addressed, you've got some reading to do :-D

To search strings, build auto-complete in redis and other cool things...
How do I search strings in redis?

Why using MongoDB over redis is smart when searching inside documents... What's the most efficient document-oriented database engine to store thousands of medium sized documents?