Can I turn my iPhone 4 to a 4s?

IPhone 4 to 4s

As far as I know no. It's a separate thing-- that's like asking for your iPhone 2 to turn into a 5. I think.

Update it on iTunes

Well you can swap it but you will have to pay the extra

You can jailbreak your 4 and get "siri" like apps, and other display feature that can make your phone seem like a 4s.

I suggest no

Yes Jailbreak it then watch this