Please help me with SQL custom search

I’m doing a search query that must search in the post meta values, that are stored in postmeta table. I have the same ID on both tables(I mean the same ID for each post) and want to include postmeta “meta_key” and “meta_value” in searched fields, as in the following code: (I hope you understand what I want)

SELECT post_id, meta_key, meta_value FROM $wpdb->postmeta
,
 (SELECT *
     FROM $wpdb->posts
         WHERE NOT wpdb->posts.post_status = 'inherit'
         AND (wpdb->posts.post_type = 'page' OR wpdb->posts.post_type = 'post')
         AND (wpdb->posts.post_content LIKE '%".$term."%' OR wpdb->posts.post_name LIKE '%".$term."%' OR $wpdb->postmeta.meta_value LIKE '%".$term."%')
     ORDER BY wpdb->posts.post_title ASC)
  WHERE $wpdb->postmeta.post_id = $wpdb->posts.ID