Create a visible / easy to reuse token in https://github.com/settings/applications by storing the token in the application name.
Use curl to search for code (notice the per-page 100) and grep case sensitive.
curl -s -H 'Accept: application/vnd.github.v3.text-match+json' --user "TOKEN_GOES_HERE:x-oauth-basic" 'https://api.github.com/search/code?per_page=100&page=3&q=user:YOURORG+SEARCHTERM' | grep 'SearchTERM'
Availble as reusable script: https://github.com/grosser/github-grep