like so many, this is actually quite easy with ocPortal, use the "Create Block" Feature and select Main_search, there you can set multiple Parameters.
For your case, this might work
but you better Create it with the Block feature.
This is one of the documentations related to the Search
|Description||Place a search box.|
|Use||Allows quick searching for content.|
|Parameter 'input_fields'||Advanced feature. By default, you'd only have one search field on your search block (the "content" field, which will search everything). But if you're doing an advanced search (you've set "Limit To"), then you can allow the user to do more complex searches. Put all the field names you'd like to be searchable, separated with commas; after each add "=The Title The Field Should Have On Your Block". E.g. 'content=Search for,option_11=Favourite food' (this example is for a members search, where CPF ID#11 happens to store the member's food preference). You would find the field names by analysing the HTML on the corresponding full advanced search form. Default: 'content=Search for'.|
|Parameter 'limit_to'||Optionally, only search the given search hook (hook-type: 'modules/search'). Default: ''.|
|Parameter 'search_under'||Advanced feature. Only search underneath the given category ID (only applicable if "Limit To" is set).|
|Parameter 'zone'||The zone to look for the search module in. Default: search for it.|
|Parameter 'sort'||Field to sort by (must be either 'add_date', 'title', or 'relevance'). Default: 'relevance'.|
|Parameter 'author'||Advanced feature. Author/submitter/username to match with or blank. Default: ''.|
|Parameter 'days'||Only find records created within this many days, or -1 for no limit. Default: '-1'.|
|Parameter 'direction'||Direction (must be either 'ASC', 'DESC'). Default: 'DESC'.|
|Parameter 'only_titles'||Whether to search only titles. Default: '0'.|
|Parameter 'only_search_meta'||Advanced feature. Whether to search only meta data (the meta description and keywords). Default: '0'.|
|Parameter 'boolean_search'||Whether to do a boolean search (a slower search, but precise to provide exact matches). Default: '0'.|
|Parameter 'conjunctive_operator'||Advanced feature. The operator used during a boolean search (must be either 'OR', 'AND'). Default: 'AND'.|
|Parameter 'extra'||Advanced feature. Arbitrary extra hidden information to be passed through to the website's search engine, to hard-code certain search parameters. E.g. 'option_11=Sports' to force only results where CPF #4 contains the word 'Sports'. Default: ''.|
which you can find within your ocPortal installation or the Documentation.