Wildcard search using WP_User_Query()

You can use WP_User_Query() class to fetch users by various arguments. With it’s search parameter, you can search users by these columns 'ID', 'login', 'user_nicename', 'user_email', 'user_url'. Although you’ve to specify which columns you want perform the search.

 
$user_query = new WP_User_Query( array( 'search' => 'a' ) );

When searching users with the search parameter, by default WordPress searches for direct match. It doesn’t search with any wildcard even if you pass like this: array( 'search' => '%a%' ), instead it’ll escape the percentage sign. But there is a hidden gem by which you can search with wildcards.

Just put * at the beginning and/or in the end of your string. WordPress will replace * with % sign and you can search with wildcard. There is no documentation about this! 
 

$user_query = new WP_User_Query( array( 'search' => '*a' ) ); // '%a'
$user_query = new WP_User_Query( array( 'search' => 'a*' ) ); // 'a%'
$user_query = new WP_User_Query( array( 'search' => '*a*' ) ); // '%a%

Pretty neat!