I mean tons of things click... fuel pumps going out make the lines click, plug wires with high resistance click when the power pulses through it, what everyone else said, knocking from low grade fuel, how new is the car to you? is it the right dipstick?

It is something you have to chase down

 

It's probably just your lifters not getting enough oil. Common issue with the 1.8t. Try a lighter weight oil or an oil additive cleaner like Justice Bros. Or maybe you are due for an oil change.