Boolean logic is used to define the relationship between the terms in your research statement or question. And is used to combine different ideas, Or is used to combine related terms or synonyms, and Not is used to eliminate unwated terms. Not is rarely used.
You can search for articles in a variety of databases at once using WorldCat Local. Simply click on on the tab Articles.
Here are two examples of useful articles found using the search strategy "informed consent" education
http://newfirstsearch.oclc.org/dbname=WorldCat;done=referer;FSIPoclc/428529914
If you find your results are not quire what you want, try a more focued approach by searching specific databases. Below is a short list of databasaes. More can be found on this page, A-Z List of Databases.