To search based on custom objects and/or fields, you will need to use the Search Object Actions. Using this action, you will be able to select any object or any field, including custom ones, that are in your Salesforce account. If you do not see the field you are looking for, there could be 2 main reasons. The first is you need to refresh the schema of the recipe. If that doesn't work, make sure that the account used to connect Workato with Salesforce has access to that particular object or field.