You will need to decompile the client and change the character page link to your link, since it's pretty much hardcoded into the client. There's not much you can do besides changing that. Also, what you could do is, I guess encourage users to manually check character pages or embed a character search somewhere, either game page or homepage. If the client is taking you to FoL charpage link, then the charpages are provided with the files and you'll only have to change the link in the decompiled client.