They should apply for Chinese tourist visas for their entry into China.
Basic required materials for application:
1. The valid passports must have at least six months validity left before expiration and at least one blank visa page left
2. Completed visa application forms with passport-size photo affixed
3. Their flight tickets and hotel reserve(may be required)
Besides these, for your U.S client, a valid Malaysian visa or residence permit is also required for his application.