can I grep both compressed files and uncompressed files using the same command

I am trying to make a script for grepping log files located in /var/log/. I am able to either grep uncompressed logs or compressed logs (as a result of log rotation) but have not been able to do both in one command (i get "Binary file (standard input) matches" when I try to do so), is it even possible to do such a thing? thanks!