Tex-Mex accordionist Flaco Jimenez may today be best known as one of the tail winds of the Texas Tornados. But to many pop and country performers, his 40-year career has made him a legendary king of the squeeze box. That’s why such stars as Linda Ronstadt, Los Lobos, Dwight Yoakam, and John Hiatt signed on for this multicultural exchange. Jimenez introduces jazz and blues strains into traditional conjunto dance music and zippy mariachi frills into contemporary country. Of the collaborations, Harris’ elegant rendition of Butch Hancock’s ”West Texas Waltz” and Hiatt’s plaintive ”Across the Borderline” work best. Occasionally things get as campy as Xavier Cugat and Charo, but mostly Partners is as delightful as a Margarita on a hot afternoon.