Hi Fernando,

When you say distributed in 3 level, do you mean across 3 fields and all the 3 fields are MSP Fields?

What are the number of values n each of the MSP field?

Anyway if you had few values and in order to search for a MSP fields this is what you have to do

Create a Custom Long Text field and using a workflow or process builder update the custom field with the values from the MSP field.

This is how the workflow configuration will look like

Create a custom long text field on the object

create a workflow rule on the object

evaluation criteria: created and everytime its edited

rule crtieria: formula evaluates to true and the formula is

NOT(ISBLANK(MSP_Field__c))

use the insert field button to select the field API Name of the MSP field

Immediate Action: Field Update

Field to Update: Long Text field

use formula to set the new value and the formula is

IF(INCLUDES(MSP_Field__c, 'Value1'), 'Value1', NULL) + ' ' +

IF(INCLUDES(MSP_Field__c, 'Value2'), 'Value2', NULL) + ' ' +

IF(INCLUDES(MSP_Field__c, 'Value3'), 'Value3', NULL) + ' ' +

IF(INCLUDES(MSP_Field__c, 'Value4'), 'Value4', NULL) + ' ' +

and so on

IF(INCLUDES(MSP_Field__c, 'Value25'), 'Value25', NULL)

Save,Done and Activate the Workflow rule

In Salesforce all Text fields are included in the search