is there a plugin where you can tp from server to server with a portal without a client for all users???
Here's the most recent post of the exact same thing you want: http://forums.bukkit.org/threads/cloud-server-plugin.79199/ You're going to need to find a very advanced developer.
Did you read the thread? You have to actually read the comments if you want to be educated about it. Unless you find someone who knows how to do this, and is willing to do it for free, you're going to be paying quite a bit of money for this.