Filter and display database row based on two or more columns

Where and how to filter and display data based on two or more columns or fields in a database table?
The database table consists of the following columns or fields, among others:
[list]ID (the entry id)
user_id (the id of the user who created the entry)
ProviderID
RequesterID[/list]

Currently, my filter code in the Conditions box is:

<?php
$user = \JFactory::getUser();
return array('BayanihanAdminDispatch.providerid' => $user->id);
?>

This code displays only the data where the logged-in user's ID is the same as the ProviderID.

In one instance, I also want to display the data or rows where the logged-in user's ID is the same as the RequesterID. In other words, if either of the two fields - ProviderID OR RequesterID, is the same, then it should be displayed.

In another instance, I want only the records where both the ProviderID AND the RequesterID are the same.

I've been googling for the correct code for 3 days already and still no luck.

What is the correct code and how do I go about it, please? Thanks in advance.

Thank you very much Bob. I would not have made it without you pointing me to the exact tutorial. The code I now use:

<?php
$user = \JFactory::getUser();
return array (":BayanihanAdminDispatch.providerid = '$user->id' OR BayanihanAdminDispatch.requesterid = '$user->id'");
?>

.... and it works!

Tip: the colon as well as the double quotation and single quotation marks are really important to create the correct syntax.

Thank you very much Bob. I would not have made it without you pointing me to the exact tutorial. The code I now use:

<?php
$user = \JFactory::getUser();
return array (":BayanihanAdminDispatch.providerid = '$user->id' OR BayanihanAdminDispatch.requesterid = '$user->id'");
?>

.... and it works!

Tip: the colon as well as the double quotation and single quotation marks are really important to create the correct syntax.