Metropolitan Research Associates subleased 16,915 square feet on the 19th floor at 666 Third Ave. from the law firm of Oppenheimer Wolff & Donnelley.It will use the space as its New York headquarters. 666 Third went through a major renovation in 1999 and the space, fully wired and built, was ready for immediate occupancy. The building is 98 percent leased. Ken Rapp and Jordan Mandel of CB Richard Ellis represented Oppenheimer Wolff. M. Myers Mermel of Tenantwise represented the subtenant.