While they may not read you "Miranda" at the time they arrest you, they most definately are SUPPOSED to tell you that you are under no obligation to answer any questions without legal representation. Once you tell them you want a lawyer, ANYTHING you might have said would be inadmissable, as they are required to stop questioning you at that point.
A cop will try (and usually succeed) and scare you into talking. The old "I can help you" or "You can make it easier on yourself" routine generally works for them. It's thier job to get you to cooperate in your own demise, by whatever means nescessary. Most folks don't stop to think that once the cop arrests you, it's pretty much out of his hands. The detectives sometimes take over to get more evidence, but usually the States attorney takes over with the evidence they have, relying on the fact that 90% of all people will spill thier guts from fear. They are not going to cut you any slack for cooperation, they WILL scare you with the "You are facing 80 jillion years, and if you make us take this to trial, we're going to give you the max" routine. This has been deemed coersion in alot of jurisdictions.
If you can afford one, get an attorney. Tell him/her that they questioned you after you stated you wanted a lawyer. Tell your lawyer the circumstances surrounding the search. I'd say you'll get off.
Could you imagine the state of affairs the legal system would be in if EVERYONE took thier case to trial instead of plea bargaining? It would come to a grinding halt!!! Our constitution (whats left anyway) prohibits the very type of system we now operate.
Cops are a necessary evil