searching for members in wordpress

Question

Probably this plugin is using user_meta table. Your query should looks like this:

$args = array(
    'meta_key' => $_searchedWhat,
    'meta_value' => $_searchedFor
);

$users = get_users($args);

For more informations look into documentation: get_users

EDIT: Unfortunately, that plugin is storing all data into one field, so you cannot query users by single field. You should use custom fields in posts or create own meta boxes with inputs that will store each field separately.