add custom field to search wordpress code example
Example 1: wordpress search in custom fields
If someone is looking for a solution to this problem is to recommend the plugin:
https://wordpress.org/plugins/acf-better-search/
Example 2: wordpress search in custom fields
So, I did another search today and this was worked first time. http://adambalee.com/search-wordpress-by-custom-fields-without-a-plugin/