The first issue here you enter in Qatar with Business Visa it is renewable up to 90 days. Second,the company who issued you a business visa it is your sponsor, if you working visa still on process with the same sponsor you are not allowed to look for new sponsor. Third, if you came here and use business visa as your entry document and your purpose is to look for other company, still you need NOC from your sponsor, I mean from the company who issued you a business visa.