Create a relationship by matching strings between two columns from different tables

Hi everyone, 

I would like to create a relationship between two columns from different tables like in the attached screenshot. Ideally it would be nice to do it in power query, rather than using DAX, but its also fine with whatever works. 

I would like to join the Lectures tablesto the subjects table, which have no specific position of delimiter, only that lectures contain strings in subject.

Any help is highly appreciated. 

Thanks