You can't, only 4.3.3 is able to be jailbroken. You can't upgrade to 4.3.3 either, you will be forced to upgrade to 4.3.5 which there is no jailbreak for. You are going to have to wait until iOS5 is released and then wait for the jailbreak to be released. The good news is devs have stated they have already found 5 different exploits with the iOS5 betas so, based on that, a jailbreak should be available for iOS5 not too long after it is released which should be some time in October.