How to do substring search among (starred) repositories?

When searching for e.g. “oard” the result will contain matches like “999oard” and “something-oard” but NOT “board”, so substring search does not seem to be possible freely. 
Is there a special syntax to search for substrings or regular expressions?

Hi @johann-petrak

Thanks for being a part of the GitHub Community Forum!

This topic has already been opened and is being discussed in another thread here: https://github.community/t5/How-to-use-Git-and-GitHub/Search-for-code-containing-string/m-p/10342. In an effort to keep the Community Forum organized and make it easier for other users to find information, we ask that users continue the conversation in existing threads, instead of opening new ones about the same topic. For this reason, I’ll be closing this topic, and you can continue the conversation in the original thread, if you’d like.

Thank you again for being here!