I'm searching for software which can solve 3d IBVP like PDEtool in Matlab (user-friendly GUI, easy to learn how to use). What could you advise to me? (ANSYS,COMSOL,OpenFOAM are too difficult for me)
You may want to consider PDE2D. Despite the name, it also applies to 3D problems. The advantage of this software is that it does provide a GUI based interface. You can download and use a free trial version for an unlimited amount of time, but there are limitations to the size of the problems that you can solve in the free version.