I am m.sc with biotechnology done 2004, working in pvt. organization as marketing manager, want to go in R&D field which was my aim what do?

I am m.sc with biotechnology done 2004 with 59%, working in pvt. organization as marketing manager, but i want to go in R&D/teaching field which was my aim, what do? i cant leave my present job because i have to also rum my family please suggest me what kind of additional course i do without leave?