jsf 2 - Making AT-LEAST any one of Input Fields as Required in JSF Form -

this question has answer here:

• jsf multiple input text (one of them required)
• how validate if @ least 1 of multiple input fields entered? 2 answers

i want make at-least 1 of filed required in form.

for example:

<h:form id="searchform">     <h:outputlabel value="user name:"/>     <h:inputtext value="#{searchbean.username}" id="user_name"/>      <h:outputlabel value="location:"/>     <h:inputtext value="#{searchbean.location}" id="location"/>      <h:outputlabel value="date of birth"/>     <p:calendar value="#{searchbean.dob}" id="dob"/>      <p:commandbutton value="search"/> </h:form> 

in above form has there 3 input fields:

• user_name
• location
• dob

and searches based on given criteria.
want make user enter at-least one of above fields required make search happen.
how use required validation above scenario work.
please suggest wok around!