Hey Ricardo,
To fetch data from your partners system, you will have to use their API.
EDIT: You may be able to configure Web Hooks to communicate with your partners system, as well. Webhooks are also described in the Developers site linked below.
If your partner needs to fetch or push data into Marketo, they can use our REST or SOAP API, details of which can be found here:
developers.marketo.comWill