Trading other's money through a company?

I want to set up an company in which clients come and they give me some money and I trade their money and make some profits and give some percentage of profits to them. Working similar like mutual funds, but not exactly like them because I agree to trade only if and if that person comes to my office and meets me personally. For that we will write a written document from a lawyer and me and the client both will sign it for security for their money. Is this thing legal? If I want to make it legal what is the process ?
Is setting up a consultancy pvt ltd enough or there should be any other company registration ?
What is the process for doing so ?

You should check this.