Make Cards more clickable

I'm creating a flat-ish responsive website, which let's you vote 4 certain topics.

I'm displaying songs (but it could be whatever) in a flexbox grid system with 4 different colours. Each song is clickable and adds 1 vote to the counter. (NOTE: These 4 options are over displayed over the full screen, such as kahoot)

Here is a screenshot of what I've made at this point.

My problem is that these cards just don't feel clickable yet. I know, as the conceptor of the design, that it is clickable. However, I feel like it is not obvious - or not enough at least - for any random user.