Should game logic be on client or server?

I'm creating a simple multiplayer turn-based game.

I can't decide where to draw the line between putting all the logic on the client or on the server.

Should the client be used just to send input to the server and print/display the responses?(This is my current solution, but seems to make the client too "stupid")

If not, how do I decide what goes on which side?

The game is very simple so I do think I could have any lag or bandwidth problems in any case.