installation of QT 5.8 or QT 5.6 & PYQT 5 (python 3)

I want to install QT 5.8 My system already has PYqt 5 installed . I want to use QtWebEngine . Even though my system has Qt5.5.1 installed but there is no QtWebengine libraries installed.
https://wiki.qt.io/How_to_Try_QtWebEngine

I followed this link but it was giving error 'Unable to find file for inclusion qt_parts' when I did qmake -r

Is there any foolproof way for installing qt 5.8 so that I can import QtWebengineWidgets in python interpreter ?
I'm using ubuntu 14.04
I want to install in python virtual environment.
It's urgent