How to jailbreak a iPhone 4 that run on iOS 7.0.3?

Please some answer I'm waiting.

Http://google.com/search?

Hope I helped!

Protip: Google is your friend

There isn't an iOS 7.0.3 jailbreak yet. Stay tuned with Evasi0n, they are on the verge of jailbreaking it.

You don't
it completely ruins your phone and takes up all your space

You can't jailbreak yet see www.howtoidevice.com for Details.

IOS 7 Jailbreak hasn't come out yet. It will take some time. IF you see "free iOS 7 jailbreak!" DO NOT download it! Wait for trusted tech websites to confirm it. It is usually preceded by a tweet from some well-known jailbreakers. It takes time for jailbreaks to come out.