Hello! 

I've found these examples in the dictionary: 

I haven't seen him yet.
Have you had your lunch yet?

In those two sentences "yet" is used as an adverb, with the same meaning that you mentioned (until now).

The weather was cold, yet bright and sunny.
Her advice seems strange, yet I think she's right.

In these two, "yet" is used as an conjunction. You can replace "yet" with "but" and the sentence has the same meaning.

You can take a look here: http://www.macmillandictionary.com/dictionary/british/yet , where there are more examples and explanations.