Checked suit, striped shirt and paisley madder pocket square make three patterns (I don't count the oxford weave of the necktie and you shouldn't either). Click on the photos to see them enlarged.
And argyle socks make four.
The key to pattern mixing is to keep the scale of the patterns different so they don't conflict with each other. This particular mix might be a bit much for an office but I was headed for an afternoon art exhibit where some complexity is not out of place.