How would you educate your client if the project reveals some complex parametres that needs to be worked out?

By having a detailed meeting with slide projector with the presence of some of your team heads.

This should be done at the planning phase by involving the subject matter experts with the client and his/her internal rep.

This is definitely going to be a challenge. And it will require some homework before you actually need it. First you should get your client absolute trust. Then avoid major surprises. After that pre meetings with one or two of your closest client's reps. And final the big meeting to represent main client representatives. Documents and numbers are important but trust is main key . 

By face to face meeting, in this meeting you must have a support documents(statsticals - docs) and the solving of that problems.

Making him questions about incoming contingencies and creating the need for him to learn. You can only educate what others want to learn.

in case of any complex in the project i will arrange a meeting to the clients face to face and give brief presentation according to relevant facts and with documentation which should be easy understandable to all the cleints and ensure them the solution of problem as soon as possible.

Prepare FAQ about the difficulties or problems. share with your kind with powerpoint presentation and have a session with them so you can solve the problem.

 The process should be well recorded in the communication management plan of the project. Set a meeting with the Project Sponsor who happens to be the Client to discuss the parameters may it be complex or not or new to the Project as this will bring impact may terms of time, cost and quality of the Project. The things, as Project Manager, we want everything fair and square in temrs of delivery of the Project and in terms of business objectives (and well documented too) - as an organization as well. 

Come prepared with a risk assessment, resource needs, trade offs, costs and timing. A face to face meeting is better for discussion of issues.

Prepre a risk analysis study report showing the problems and suggested solution options and submit the report to the client and then conduct a meetings to covince and agree upon.

Quite risky if not well geared to answer all suspicious questions driven by situation ambiguity.

Plan A: Clear complexity by simplifying and interpreting parameters with terminology close to client background and common experiences and examples.

Plan B: Step into client shoes and prepare answers to all "Why" and "What if" questions he may ask.