For example

'energy, education, research' with the boolean 'OR' would find records containing 'energy' or 'education' or 'research', whereas changing the boolean to 'AND' would only find records containing 'energy' and 'education' and 'research'. Wildcard character is % which is added to both sides of the keywords but you can use it within a keyword i.e. 'education%research' which would catch 'educational research' and 'education on energy research'.