Framingham Public Library supporters are searching for local volunteers to help raise private donations to supplement state and town funding for the new McAuliffe Branch Library project in the Nobscot section of town. Organizers are hoping to raise $600,000 in supplementary funds, and are looking for volunteers who can research and talk to potential donors, complete back-office tasks related to the fund-raising campaign, and help with special events. The Framingham Public Library Foundation has raised about half of its goal in the past 18 months, president Ruth Winett said, and is making plans for benefit events this year. The estimated $8.6 million project will include construction of a one-story, 17,000-square-foot building on Water Street that will better suit the library's changing needs, officials said. The project received $4.2 million from the Massachusetts Board of Library Commissioners in October, and supporters will ask Town Meeting to approve $3.8 million in town funds in April.