diff --git wp-includes/meta.php wp-includes/meta.php
index 8a9dad9..d3e4f82 100644
--- wp-includes/meta.php
+++ wp-includes/meta.php
@@ -708,7 +708,7 @@ class WP_Meta_Query {
 		// Split out the meta_key only queries (we can only do this for OR)
 		if ( 'OR' == $this->relation ) {
 			foreach ( $this->queries as $k => $q ) {
-				if ( ! isset( $q['value'] ) && ! empty( $q['key'] ) )
+				if ( ( empty( $q['compare'] ) || 'NOT EXISTS' != $q['compare'] ) && ! isset( $q['value'] ) && ! empty( $q['key'] ) )
 					$key_only_queries[$k] = $q;
 				else
 					$queries[$k] = $q;