Dictionary.com defines racism as thus:
1. a belief or doctrine that inherent differences among the various human races determine cultural or individual achievement, usually involving the idea that one's own race is superior and has the right to rule others.
2. a policy, system of government, etc., based upon or fostering such a doctrine; discrimination.
3. hatred or intolerance of another race or other races.
So unless your preferences constitute a belief that is synonymous with any part of that definition, then no, a preference is NOT inherently "racist". I think that word gets used way too frequently lately, and has become a crutch in many arguments. That said, there is a whole lot of racism in the world, but a simple preference like "I like Asian women" is NOT racist. Racist would be saying, "I like Asian women because they are superior to women of every other race". That would start the racist ball rolling. Simple preferences that don't use any race based qualifier to insist that the race is "above" others, is not inherently racist.