LightningDataTableComponent.cmp

<aura:component implements="forceCommunity:availableForAllPageTypes" access="global" controller="LightningDataTableController">
    <!-- attributes -->
    <aura:attribute name="data" type="Map"/>
    <aura:attribute name="filteredData" type="Map"/>
    <aura:attribute name="columns" type="List"/>


    <!-- handlers-->
    <aura:handler name="init" value="{!this }" action="{!c.init }"/>
		
    	<span>
        	<lightning:input onchange="{!c.searchTable}" type="search" label="Searh" variant="label-hidden" placeholder="Enter search term" aura:id="SearchBox"/>
        </span>
    	<br/>
        <lightning:datatable
            columns="{!v.columns}"
            data="{!v.filteredData}"
            keyField="id"
        />
    
</aura:component>

LightningDataTableController.cls

public class LightningDataTableController {
	@AuraEnabled
    public static List<sObject> fetchData() {
        //Query and return list of Contacts
        List<SObject> objRecords = [SELECT FirstName, LastName,Email from Contact LIMIT 10];
        return objRecords;
    }
}

LightningDataTableController.js

({
    init: function (cmp, event, helper) {
        cmp.set('v.columns', [
            { label: 'First Name', fieldName: 'FirstName', type: 'text' },
            { label: 'Last Name', fieldName: 'LastName', type: 'text' },
            { label: 'Email', fieldName: 'Email', type: 'text' }
        ]);
        var action = cmp.get("c.fetchData");
        action.setCallback(this, function(response){
            var state = response.getState();
            if (state === "SUCCESS") {
                cmp.set("v.data", response.getReturnValue());
                cmp.set("v.filteredData", response.getReturnValue());
            }
        });
        $A.enqueueAction(action);
    },
    searchTable : function(cmp,event,helper) {
        var allRecords = cmp.get("v.data");
        var searchFilter = event.getSource().get("v.value").toUpperCase();
        
        var tempArray = [];
        var i;

        for(i=0; i < allRecords.length; i++){
            if((allRecords[i].FirstName && allRecords[i].FirstName.toUpperCase().indexOf(searchFilter) != -1) ||
               (allRecords[i].LastName && allRecords[i].LastName.toUpperCase().indexOf(searchFilter) != -1 ) || 
               (allRecords[i].Email && allRecords[i].Email.toUpperCase().indexOf(searchFilter) != -1 ) )
            {
                tempArray.push(allRecords[i]);
            }
        }
        cmp.set("v.filteredData",tempArray);
    }
})