How do I change the LolClient icon on Mac?

I play League on my MacBook Air, and I want to change the LolClient icon. This is so that when I have LolClient is open, it is disguised as another app, and when my dad checks my dock, he won't see anything suspicious. I have tried replacing every single .icns file in the directory, but I have only managed to change the LolPatcher and League of Legends icon, never LolClient itself. Any tips? Btw I'm running the latest Mac OS, El Capitan at the moment.