Do your homeworkYes, there's probably one magical candidate out there who will match all 10+ must-haves. Chances are, they're not interested. If a req seems unrealistic, the first thing you have to do is research. Check out similar positions to make sure that your client didn't put you in a lose-lose situation.
Pick up the phoneSo, you've done your research and you can confidently say the req is unattainable. Now what? This is your opportunity to reach out to the client. Don’t try to take control and rework the requirements without first explaining the problem. Even if you’re an expert on their industry, you’re not a mind-reader.
Trim the fatTime to see your communication skills in action. Work with the client to prioritize their list. Break down every requirement and pinpoint the ones that are truly the “must-haves” to be successful in the role. Flesh out the list and do your best to narrow it down to 3 or 4 absolute requirements.