Is this just a logic or experience about mind(reality)? While doing self enquiry kind of meditation(also doing vipassana) there is feel of understanding/experience/logic that make myself convinced(but not strongly) that "me" is not the thoughts or the body or sensual experience. I don't continuously feel this, but I find concentration, calmness etc getting better. 

What is this am I experiencing? 

How to go beyond this? 

And some teachings says that if you can disassociate ourself from mind and body then we can experience oneness(or conciousness), but I don't experience oneness or anything that I haven't experience before except the feeling of dissociation, why?
Sounds like the hinderances have been temporarily tamed to some degree.     

Oneness as I experience it using metta, self investigation and mindfulness just means there doesn't nessasarily have to be a distinction made by us human beings between me and other, us and them, tree and it's background, hand and fingers, sky and ground, good and bad, out and in, foot and ground, right and left, eyelid and eye,  you and me, up and down and so on. If no distinctions are  taken for granted one can transcend only perceiving distinctions and percieve everything as one yet distinct. 

Dissociation with the concept of oneness or dissociation with needing to bring on oneness might be desirable as oneness can so easily be clung to.

How do you get beyond? Simply don't try to get beyond, that detached kind of  attitude is in harmony with getting beyond.  Keep at it, it sounds to me like your doing alright.