Meta Query – Ajax Key
$meta_query = array( 'relation' => 'AND', array( 'key' => 'ajax_key', 'value' => '$_REQUEST['key']', 'compare' => '=', ), );
$meta_query = array( 'relation' => 'AND', array( 'key' => 'ajax_key', 'value' => '$_REQUEST['key']', 'compare' => '=', ), );