One year ago @t31os answered a post with a code I can’t access:
http://wordpress.org/support/topic/search-custom-field-data
His answer…
I was feeling adventurous, so i wrote a simple plugin to do it..
http://wordpress.pastebin.ca/1736605
The post search in the admin will now also check against the meta keys and meta values when checking for matching posts… 😉
Is there a way to get that code so I can use it?
Thank you very much
Patricia
Don’t know what’s wrong with that link but you can see an answer to a similar question
how to filter post listing (in WP dashboard posts listing) using a custom field (search functionality) ?
Its just what you are looking for.