Apart from obvious activities like test data creation, test case
execution, bug reports...what other initiatives can a QA engineer ,
take which will help raise his value to the project/Client.
You can only do what the situation and context permit you to do.
In some shops testers get to review the Requirements before they are finalized. If that's the case, spend some time digging in an understanding the Requirements, pointing out any inconsistencies and unclear portions. If you are part of a formal Requirements review process, you can make sure that all parties (Product Management, Development, Test) all have the same understanding of the Requirements. That is a great way to avoid bugs, and thus a strong value add that you can provide.
Periodic summary reports are a service that testers provide in some shops. A report containing the bug count, the list of open bugs and priorities, etc - can be of value to the team.
If your shop conducts bug triage, you can provide extra value by helping to lead the effort - provide bug lists to the participants, be the scribe for the meeting, perhaps update the bug reports in real time as the triage occurs. The provide everyone with the outcome of the triage session.
Basically, testing is a service to the larger team. Find out what they need to be as effective as possible and find a way to help deliver that.