Querying the `wp_usermeta` Table

I am trying to figure out how to extend my plugin so that it queries the wp_usermeta table when I search for users in the Dashboard, i.e. on the “/wp-admin/users.php” page. I am thinking that I can use the ‘user_search_columns’ filter to hook into the search, modify the columns that the search queries, and get the desired results. However, I have not yet been able to get that approach to work.

Does the ‘user_search_columns’ hook query the wp_usermeta table? Do you have any suggestions for how to improve upon this approach or any suggestions for different approachs that I could take that would help me to accomplish my goal?

For your reference, here are links to the Codex for the ‘user_search_columns’ filter and to a pastebin for my code:

Codex
http://codex.wordpress.org/Plugin_API/Filter_Reference/user_search_columns

Pastebin
http://pastebin.com/LuFeG1jg