Index: wp-includes/class-wp-xmlrpc-server.php
===================================================================
--- wp-includes/class-wp-xmlrpc-server.php	(revision 21548)
+++ wp-includes/class-wp-xmlrpc-server.php	(working copy)
@@ -1425,6 +1425,10 @@
 				$query['order'] = $filter['order'];
 		}
 
+		if ( isset( $filter['search'] ) ) {
+			$query['s'] = $filter['search'];
+		}
+
 		$posts_list = wp_get_recent_posts( $query );
 
 		if ( ! $posts_list )